With a trend towards higher performance and multiple functional portable information terminals, power consumption of portable information terminals tends to increase. However, there is a limit to electric power supplied from batteries mounted on portable information terminals. In response to this, a portable information terminal in recent years mounts a multi-core CPU with built-in multiple cores and dynamically increases or decreases the number of operating cores while observing a CPU load to reduce power consumption of the entire CPU while securing user's operability.
As a technique for controlling the number of operating cores, a core control technology for calculating a CPU load for individual threads and determining the number of operating cores based on the number of threads whose CPU load exceeds a threshold, has been available. A related art is, for example, Japanese Laid-open Patent Publication No. 2013-92874.